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Peter Abrams: an appreciation

Peter Abrams has retired (I think; he’s been easing into it for a couple of years and so I’m not sure if he’s officially 100% retired just yet). I don’t know Peter very well personally–we’ve chatted a number of times, and reviewed each others’ papers–but I do know his work quite well. Indeed, I still have two filing cabinets full of paper reprints, which I began accumulating when I started grad school and didn’t stop accumulating until a couple of years ago. They’re organized by author. I have so many Peter Abrams reprints that I need two file folders to hold them all; he’s the only author for whom that’s true. So by that measure of “impact”, Peter Abrams has had more impact on me than any other ecologist. And given how carefully I read many of those papers (filling the margins with notes), and how I developed into someone who (I think!) approaches ecology in much the same way as Peter does, it’s fair to say he’s had as much impact on me–by any measure–as any ecologist. So I thought it appropriate to mark his retirement with an appreciation. Hopefully, folks who knew Peter better than I did will chime in in the comments.

Peter Abrams was one of the world’s leading theoretical ecologists. His publication record is outstanding. He has something north of 150 papers I believe, many first-authored (often sole-authored) and mostly in leading journals. His interests centered on fundamental issues in population and community dynamics, which he preferred to explore using simple differential equation models of small numbers of species (what Bob Holt calls “food web modules”). Often, he would work on the boundary of analytical tractability, so his papers often combined analytical results for simple limiting cases with numerical simulations of more complex, analytically-intractable cases.

Peter was probably ecology’s greatest contrarian. He loved pushing back against the conventional wisdom. No one was better than Peter at exposing how much of what ecologists think they know is based on fragile conceptual foundations, unrecognized implicit assumptions, overgeneralization from special cases, and selective focus on certain possibilities to the exclusion of other, equally-plausible possibilities. Many of his earliest papers attack the idea of “limiting similarity”, the notion that there is some absolute limit to how similar coexisting competitors can possibly be. Peter returned to this idea often in his later work. Other early work showed that predator-prey coevolution often does not take the form of an “arms race”. Peter showed how coevolution of competing species doesn’t necessarily lead to character displacement, and in fact can to lead to character convergence. I’ve done a bit of work building on this idea of character convergence, and I think it would be a great hypothesis for some ambitious student to try to test empirically (it’d be a hard experiment, but if it worked it would be a Science paper) Peter wrote a nice review back in the mid-90s of all the reasons why species diversity might not peak at intermediate productivity levels. He did a bunch of modeling work on adaptive foraging in patchy habitats, showing that we typically don’t expect adaptive foragers to exhibit an ideal free distribution. He identified circumstances in which increasing density-independent mortality can actually increase population size, and circumstances in which species that share resources or predators can act as mutualists rather than competitors. He showed how extinctions brought on by gradual directional environmental change often will involve sudden crashes from high population size, rather than being preceded by gradual declines to low population size. Occasionally, I do think his contrarianism went too far. Some of Peter’s papers come off as just introducing arbitrary complications, purely for the sake of showing that the world is complicated. But those are the exceptions. Overall, I think ecology would be much better off if we had more contrarians like Peter. (I should emphasize that I have no idea if Peter sees himself as a contrarian. All I can say is that’s the impression his papers give me, which I admit may say as much about me as a reader as it does about Peter as an author).

Peter was a theoretician’s theoretician–he was very precise, and very alert to how imprecision in how we define our terms can lead us astray. In the ’80s he pointed out just how tricky it is to define what we mean by “competition”, for instance because species can negatively affect one another at an individual level without necessarily reducing one another’s population sizes. He has a very thoughtful paper about how to individuate and count “limiting factors”, which is something you have to do in order to properly interpret and test the competitive exclusion principle (the number of species coexisting at equilibrium can’t exceed the number of limiting factors). That paper suggests that Hutchinson’s “paradox of the plankton” (how do so many species of algae coexist on only a few limiting factors?) is actually a non-paradox, and only looks paradoxical because we’re not distinguishing and counting “limiting factors” properly. He thought hard about the definition of “indirect effects”, and how to distinguish between different kinds of indirect effects. That work revealed serious problems with standard experimental designs used to tease apart “density-mediated” and “trait-mediated” indirect effects. And he almost single-handedly exposed the conceptual flaws in the once-trendy idea of “ratio-dependent” functional responses (in which the feeding rate of an individual predator depends on the ratio of predator abundance to prey abundance).

But it would be a mistake to think that all Peter Abrams did was just criticize the work of others or point out that the world is complicated (important as both those activities are). He was a pioneer of “eco-evolutionary dynamics”, from long before that term existed. Some of his very first papers, from the late ’70s and early ’80s, are about the consequences of adaptive foraging for coexistence and food web stability. And in 1993 he derived the canonical equation of “adaptive dynamics”, an approximation to quantitative genetics which makes modeling eco-evolutionary dynamics much more tractable than it otherwise would be (others derived the same equation independently around the same time, via other arguments). The population- and community-level consequences of behavioral and evolutionary adaptation is a key theme running through much of Peter’s work. Peter also did a lot of work on the behavior of fluctuating, nonlinear systems. And he made important contributions in areas I know less well, like modeling life history evolution and sexual selection.

It’s probably the fate of the contrarian to be underappreciated, especially if he’s also a theoretician. And while Peter certainly was very well-known and well-cited, he didn’t win a lot of the battles he fought, at least not in the minds of non-theoreticians. Unfortunately, ecologists today still mostly believe in limiting similarity (that’s the basis for much of “phylogenetic community ecology”, for instance), they mostly believe that competition always selects for character displacement, they mostly believe that high density-independent mortality rates prevent competitive exclusion, they mostly believe that the diversity-productivity relationship must be humped…But if Peter’s influence wasn’t widespread except among theoreticians and the more theoretically-minded empiricists, well, I think that’s just a measure of how rare it is for any one person to have really wide influence over an entire field. Especially if that person is trying to push back against established ideas.

Peter wasn’t just a prolific author, he was an extraordinarily active reviewer. A couple of years ago he told me that he refused to do more than one review per week! His example is one to keep in mind next time you’re tempted to turn down a review request because you’re “too busy”. And as someone who’s been reviewed by Peter, let me tell you, he was not one to just toss off sloppy reviews! Peter was as thorough and rigorous as any reviewer I’ve ever encountered in all my years as an author and editor. He knew the literature back-to-front, and always let you know if he thought you were reinventing the wheel or putting old wine in new bottles. I can’t say I always agreed with his reviews, but they always made my papers much better.

As I said, while Peter’s work is hardly unknown, I do think it’s underappreciated. But it’s never too late for that to change. So if you’re looking for something to read, Peter’s retirement is as good an excuse as any to dig into his “back catalog”. You’ll be well-rewarded.

23 thoughts on “Peter Abrams: an appreciation”

I also have had few personal interactions with Peter but have read and valued much of his work with, like you, an extremely thick folder of paper copies of his work (kind of dates us doesn’t it). The 1993 paper you mention is the acme for me – unifying behavior, quantitative genetics and game theory elegantly and exactly. And dealing with multiple species and multiple traits at the same time. It was a tour de force that took most of the adaptive dynamicists years to catch up.

But one of the few personal interactions sticks out in my mind most. I was a 2nd year graduate student giving my first talk at ESA (it was on coevolution of mutualisms using the evolutionary dynamics/game theory approach that he & Joel Brown had more or less invented – this was before the phrase adaptive dynamics had even really caught on). I emailed him saying that I would value his feedback if he had time to attend. Despite me being a nobody and him being a famous ecologist, he showed up, stayed after the talk and spoke with me for 20 minutes giving me valuable feedback and was extremely kind and helpful. I am even more impressed these days given how hard I sometimes find it to even make my own student’s talks at ESA. He is truly a generous individual who values the kinds of things that are critical to the advancement of science but don’t necessarily get valued like they should any more (i.e. reviews, time with new people in the field).

I first met Peter as a grad student myself, when he came to speak at Rutgers. I scheduled a block of one-on-one time with him. At the time I found him quiet and a bit difficult to draw out–he never mentioned that he had a paper with Bob Holt in press at Ecology that was directly relevant to what we were talking about! But I don’t remember the conversation well, and in retrospect I wonder if I just talked his ear off and didn’t let him get in a word in edgewise. 😉 (UPDATE: and the more I think about it, the more I suspect that the fault was mine for not making clear exactly what it was I wanted to pick Peter’s brain about)

I agree that that original adaptive dynamics paper is one of his best, though I have others I personally like more, just because they’re closer to what I do (e.g., his 1993 paper cataloging the qualitative form of trophic cascades in a bunch of different food web modules). I think that adaptive dynamics paper is a good example of him not getting as much credit as he should. “Adaptive dynamics” is much more identified with folks like Metz and Dieckmann, who’ve been very vocal about pushing a different (perhaps more rigorous, but also much less generally-applicable) derivation of the approach.

I only have one good Peter Abrams anecdote, which I think I related in an old post but which I’ll repeat here. Back in 2000 there was a big symposium one morning at the ESA meeting on “30 Questions for Ecology in the New Century”. There were six speakers, all very famous, each talking about what they thought would be the five biggest questions in ecology over the next century. Peter was speaking in a regular afternoon session, giving the very first talk in the session, so his was the first talk we all saw after attending the morning symposium. He started off by smiling and saying “I predict that the 30 questions for ecology in the next century will be the same 30 questions as in the last century.” HUGE laugh from the audience, it was very, very funny–in part because it was very true.

Jeremy: *excellent* post.
Brian: you’ve hit the nail on the head here. If I were to use one word (besides brilliant) to describe Peter it would be *generous*. Or maybe I’d choose *thoughtful*. I remember once after a particularly ‘humbling’ committee meeting as a masters student, Peter took the time to email me the next day to re-assure me…having picked up that I was feeling overwhelmed. He said something like: “its not your work we’re worried about, its your interest in neutral theory!” 8) A few years later at a conference I was presenting my first bit of post-neutral-theory-research. Peter came up to me after my seminar and said something like ‘good presentation’. I don’t think he really felt very strongly one way or another about what I presented, but rather I think he felt that it was important to acknowledge that I was progressing as a scientist even though we really had had very little interaction for several years. I could go on and on here.

To be sure, Peter’s work is brilliant and all that…but what always impressed me the most about him was his good nature.

“It’s not your work we’re worried about, it’s your interest in neutral theory.” That’s another great line. 🙂 As far as I know, Peter didn’t have a reputation as an especially witty guy, but perhaps he should have. 😉

Thanks a lot for this excellent post. I am by no means an ecologist (though like most evolutionary biologists I know, I pretend to be one on occasion–talking authoritatively about how character displacement and limiting similarity work, etc., etc.) but I also really admire Peter’s work. However, I will certainly admit that I have not made it through much of the “back catalog” especially considering just how much of it there is; this is a situation that I am going to have to remedy. Jeremy, a suggestion/request from someone outside of this field who would like to get a better handle on a lot of this: if you find the time (and have the interest), I would love it if could put together a Peter Abrams “Greatest Hits” collection of the papers of his that you really love/feel are generally overlooked, etc. Just an idea…

Another thing about Peter’s work I tend to appreciate is that he didn’t have one big idea that he just ran into the ground. He certainly had topics he returned to a lot, and certain approaches he favored, and some recurring themes. But he was definitely more of a fox than a hedgehog. I like to think of myself the same way.

I’m a big fan as well. I thought very carefully about applying to do a post-doc with him some time ago, but didn’t in the end. I wouldn’t say I regret the decision, but I sort of wish I had an alternative reality where I could have gone off and done it as well as the other stuff that was going on at the time. Instead, I sent my first academic offspring off to do a post-doc with him after he finished his PhD, a few years later.

I don’t have any anecdotes, never met Peter, but I do remember smiling when I was reading through one of his recent papers, and counted ~27 self-citations in the reference list (they’re particularly noticeable, as most appear at the top of the alphabetical list). There aren’t too many authors who would/could do that, and they were probably all warranted.

I’m gonna enjoy going through all the links in your next post carefully now!

I’m sure the self-citations were warranted. As I’ve noted, Peter’s later work often returns to themes from his earlier work, approaching them from different angles, hence the need for him to cite his own earlier work.

Reading Peter’s papers I found I always ended up highlighting full paragraphs. Not intentionally but because it seemed that every word was important. It was aggravating and awesome at the same time. I can certainly agree with the ‘filling the margins with notes’.

Thanks Jeremy – Peter definitely deserves (and would probably be embarrassed) by all of the praise. Taking a course from him and interacting with him has been one of the highlights of my time as a grad student in the U of T department. The running joke among his students is that no matter what great idea you think you come up with, Peter will be able to think of some 30 year old paper (sometimes his own) that did it already, and probably better.

I’m really glad I came across this, even though I realize this was posted a full year ago. Thanks Jeremy for posting this, and it was nice to very briefly meet you at ESA this year in Minneapolis. I have just recently discovered your blog, and I really like it!

I was planning to teach high school until I took Peter’s undergraduate theoretical ecology and evolution class and did an undergraduate project in his lab at U of T. His class opened my eyes to the role of mathematics and concept-driven thought in understanding ecological systems that I hadn’t fully appreciated before, and reinvigorated my academic interest in ecology. When I worked in his lab, I was constantly awestruck by his limitless patience and generosity with his time, which I’m sure I frequently tested. The stories about his astounding generosity as a reviewer are not at all surprising to me. As an undergraduate in his lab, I got extremely timely and meticulous comments from him on dozens of versions of lab notes and drafts of my honours thesis, which he clearly took seriously even though I’m sure they were all horrendous to varying degrees. His mentorship was probably the single biggest reason that I both applied to graduate school in the first place, and that I got in. Five years later, I am spending much of my time in Toronto this year to be close to my partner while I finish writing my thesis at the U of Minnesota, and Peter has generously provided me with office space and introduced me around, even though he’s retired, so I can remain part of an academic community here. Last week, he casually asked what I was working on, so I sent him one of my thesis chapters in the works, and a couple of days ago he sent me incredibly useful and meticulous unsolicited comments on it. Even at the U of M, where it’s been something like 15 years or more since Peter was a faculty member, people will tell me stories about how generous he was with his students when he was here whenever I mention that I used to work for him.

Your descriptions of Peter as a theoretician’s theoretician, as a contrarian at times, and as undervalued, also ring true to me. When I was in Toronto, I overheard someone once describe a paper of Peter’s that had just come out at the time as ‘another bulletproof Abrams paper’, and the phrase has stuck with me ever since. He has an incredibly precise intuition for the assumptions and limitations of models, which I often try to channel as best I can, though probably seldom do justice. I think Peter’s precision and meticulousness stem from his unique combination of brilliance and humility that is far too rare. Unfortunately, his humility may also be one of the reasons for his under-appreciation in the often bombastic world of science. I frequently find myself trying to channel Peter, asking ‘What would Peter say?’, when reviewing my own work, in order to try to reign in some of my own natural bombastic tendencies.

As other commenters have said, I could go on and on. However, I would just like to conclude by saying that Peter has without a doubt been and will continue to be one of the most important influences in my professional life. I can only hope that Peter’s influence and legacy continue to grow so that as many others as possible can learn as much from Peter and his work as I have.

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